Quantitative organic vapor-particle sampler

ABSTRACT

The present invention concerns a quantitative organic vapor-particle sampler which can efficiently sample both semi-volatile organic gases and particulate components through the use of a unique sorbent resin coating and process. 
     The sampler of the present invention comprises in its broadest aspect a tubular device having an inlet at one end through which organic vapor/particles are introduced, an outlet at the other end through which gases exit, at least one annular denuder interposed there between which is coated on the inside surface of the annulus with a specially prepared resin absorbent, which selectively absorbs organic vapors contained in the gases introduced into the inlet, and a filter which traps and collects particles. 
     The invention further concerns a semi-volatile organic reversible gas sorbent for use in an integrated diffusion vapor-particle sampler comprising macroreticular resin agglomerates of randomly packed microspheres with the continuous porous structure of particles ranging in size between 0.05-10 μm.

This is a Divisional application of Ser. No 09/088,593, filed on Jun. 2,1998, now U.S. Pat. No. 6,226,852, which is a Continuation-In-Partapplication of abandoned U.S. Ser. No. 08/191,344 filed Feb. 2, 1994.

This invention was developed under National Heart, Lung, and BloodInstitute of the Department of Health and Human Services, AREAL, and theU.S. Environmental Protection Agency grants. The U.S. Government hascertain rights in this invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a quantitative organic vapor-particlesampler which can efficiently sample both semi-volatile organic gasesand particulate components through the use of a unique sorbent resincoating and process.

The sampler of the present invention comprises in its broadest aspect atubular device having an inlet at one end through which organicvapor/particles are introduced, an outlet at the other end through whichgases exit, at least one annular denuder interposed therebetween whichis coated on the inside surface of the annulus with a specially preparedresin absorbent, which selectively absorbs organic vapors contained inthe gases introduced into the inlet, and a filter which traps andcollects particles.

The invention further concerns a semi-volatile organic reversible gassorbent for use in an integrated diffusion vapor-particle samplercomprising macroreticular resin agglomerates of randomly packedmicrospheres with the continuous porous structure of particles rangingin size between 0.05-10 μm.

2. Background and Related Disclosures

Assessment of both the vapor and particle components of various samplesis important in a number of different situations. Accurate measurementsof phase distributions of polycyclic aromatic hydrocarbons (PAH) inindoor air and environmental tobacco smoke (ETS) are needed in order toassess exposure or danger of exposure to carcinogenic compounds sincelung deposition patterns of PAH depend on the distribution of the PAHbetween the gas and particle phases. Environmental fates ofsemi-volatile organic species are also phase-dependent becauseatmospheric reactions, and transport and deposition processes differ forgas and particulate semi-volatile species. Understanding thecontribution of organic species to visibility degradation requiresaccurate phase distribution data. Pollutant control strategies are alsophase-dependent.

Classic vapor-particle samplers, generally termed filter-sorbents, allowflow of an air sample through a chamber. In these samplers, at the endof the chamber where the airstream enters the chamber is a physicalfilter that picks up the particulate matter from the sample, as well asany semi-volatile components associated with it. At the base of thechamber is a sorbent bed which then collects any remaining gas phasematerials. These gas-phase materials are then desorbed and analyzed todetermine the presence of the material in the sample.

Some specialized filter-sorbent samplers which can detect gas-phaseorganic polycyclic aromatic hydrocarbons (PAH) have been developed.Cotham et al., developed such a sampler using polyurethane foam for thesorbent (Environmental Science and Technology, Vol 26, pp 469-478,(1992)). Kaupp et al used macroreticular polymeric resin beads to testfor PAH, which are described in (Atmosoheric Environment, Vol 26A, pp2259-2267, (1992).

Unfortunately, because these prior art sampler sorbent beds arepositioned downstream from the filter, desorption of semi-volatilecompounds from the filter creating negative artifacts, or collection ofgases by the filter creating positive artifacts, lead to incorrectmeasurements of gas-phase and particle-phase concentrations.Considerable experimental and theoretical efforts have been expended tounderstand and correct for these condensation and vaporization effects.

An important advance in vapor-particle samplers was described byPossanzini in Atmospheric Environment, 16:845-853, (1983). The samplerdescribed therein was able to test for inorganic acidic or basic gasesusing sorbents, such as sodium bicarbonate and citric acid.Additionally, Possanzini developed a different configuration for thesampler, allowing for greater efficiency while avoiding many of theproblems of the prior art samplers.

In contrast to the prior art samplers, in Possanzini's configuration thesample is pulled through an annular space coated with a specificsorbent. The filter to collect the particulate portion of the sample ispositioned downstream of the sorbent. This configuration obviates thepositive and negative artifact problem of the prior art samplers.

The Possanzini configuration allows this arrangement because of thedesign and function of his sampler. Possanzini's sampler includes anannulus through which the sample flows by positioning two tubesconcentrically to form such annulus. Other researchers have developedalternate means to produce the sample flow necessary for this samplingtechnique.

Broadly, Possanzini's improvement works as follows. when an airstreamcontaining gases and particles is moving through tubes under conditionsof laminar flow at a certain linear velocity, the particles move at thelinear flow velocity. By contrast, the gases diffuse randomly in alldirections at speeds determined only by their molecular weights and thetemperature (kinetic energy).

When the airstream flows through an annulus, the dimension of theannulus (or annuli) is designed to be close to the diffusion path lengthof the gases. This results in the gases reaching the coated walls of thedenuder where they react in an acid-base reaction. The gases are thusremoved from the airstream, while the particle portion of the sampleproceeds at the linear flow velocity of the airstream, to be removed byfiltration. Any species desorbed from the filter are collecteddownstream of the filter.

The research community was very interested in sampling organic gaseswith the clearly superior efficiency using the Possanzini sampler.However, without a specific sorbent for organic components, this was notpossible. Prior to the present invention, gaseous organic componentscould not be desorbed to make them available for analysis, much less toallow quantitative analysis.

Krieger et al (Environ. Sci. Technol., Vol 26 pp 1551-1555, 1992)developed a diffusion denuder to fill the need for quantitative analysisof semi-volatile gases, but due to its small size, this denuder had nocapacity to test the particulate phase of a sample.

Krieger's diffusion denuder uses capillary gas chromatographicstationary phase columns that can be used for direct determination ofgas-phase semi-volatile organics. This denuder is very effective atquantifying volatile organic compounds but less effective at quantifyingsemi-volatile organic compounds. This denuder has a lower capacity forgas-phase organic compounds than the integrated organic vapor-particlesampler of the instant invention.

In order to gain some of the advantages of the Possanzini approach forgaseous organic component analysis, some other differential diffusionsamplers were developed where a sorbent was used only to clean thesample stream of volatile organic compounds, rather than serve in anytesting capacity. In these systems, two separate sample chambers had tobe constructed in order to test two aliquots of each sample, one withand one without the non-reversible sorbent present. Typically each sidealso had a sorbent downstream of the filter. It was then hoped that thedifference in the collection on the filters and downstream denuders fromeach system would reflect the gaseous semi-volatile organic component ofthe sample. There was no quantitative finding available for anyparticular species in this “cleanse and test” system.

More recently, some other denuders were developed, such as, for exampledenuder, to cleanse the sample stream of semi-volatile organic speciesdescribed in Environ. Sci. Technol., Vol 22 pp 941-947, (1988). Coutantet al, developed silicon grease (Atm. Environment, Vol. 26A pp2831-2834, 1992) and Eatough et al, used filter paper impregnated withactivated carbon as a denuder coating to collect semi-volatile organiccompounds and pesticides (Atm. Environment, Vol. 27A pp 1213-1219,(1993)). Differential samplers represent an important advance overconventional samplers in the assessment of organic, gaseous species.However, as seen in U.S. Pat. No. 5,302,191, issued Apr. 12, 1994,sampling of atmospheric semi-volatile compounds remains a challenge, andis often inappropriately addressed by atmospheric chemists.

Recently, materials such as various resins have been utilized forcoating surfaces of vapor-particle samplers, described above.

Meitzner in U.S. Pat. No. 4,224,415, incorporated hereby by reference,discloses a method of making a macroreticular resin by copolymerizing amixture consisting of a monovinyl carbocyclic aromatic compound or anester of acrylic or methyacrylic acid, with a polyethylenicallyunsaturated monomer selected from the group consisting of a polyvinylcarbocyclic aromatic compound, an ester of a dihydric alcohol and anα-β-ethylenically unsaturated carboxylic acid, diallyl malcate, anddivinyl ketone. The copolymerization was conducted while the monomerswere dissolved in 25 to 150% by weight, based on monomer weight, of anorganic liquid or mixture of organic liquids which acts as a solvent forsaid monomers but are unable to substantially swell the copolymersresulting from copolymerization.

However, these resins were not successfully utilized for efficientsampling of semi-volatile organic gases and particulate components andthere still remain daunting limitations to the current integratedsampler technology in assessing volatile and semi-volatile gas speciesin a sample. While differential samplers address some of these needs,they require double equipment, and they require, as a prerequisite toobtaining correct results, that the sample be divided perfectly. Becausethe species in question is never directly recovered, it is impossible toachieve accurate quantitative results for any particular gaseous organiccomponent.

A sorbent which can be adhered to the inner surface of an integratedsampler, and from which volatile and semi-volatile organic componentscan be desorbed and assessed quantitatively, would represent animportant and dramatic advancement in atmospheric sampling.

SUMMARY OF INVENTION

It is one object of this invention to provide an improved integratedvapor-particle sampler, for the purpose of sampling semi-volatilepolycyclic aromatic hydrocarbons and other organic species, which ismore efficient than the samplers of prior art.

It is another object of the invention to provide an integratedvapor-particle sampler which eliminates artifacts in the samplingprocedure.

It is another object of the invention to provide an integratedvapor-particle sampler which contains as a component thereof an improvedannular denuder.

It is another object of the invention to provide an integratedvapor-particle sampler containing an improved annular denuder whichallows both vapor and particulate phase organic species to be recoveredand quantified.

It is another object of the invention to provide an integrated organicvapor-particle sampler whose parts can be used in several differentconfigurations, depending on the purpose of its use.

It is another aspect of the invention to provide a semi-volatile organicreversible gas sorbent for use in an integrated diffusion vapor-particlesampler comprising macroreticular resin agglomerates of randomly packedmicrospheres with the continuous porous structure of particles rangingin size between 0.05-10 μm.

It is still another object of the invention to provide a sorbent coatingwhich will not release particles when air flows over or through thecoated air sampling device.

It is yet another object of the invention to provide a sorbent coatingwhich does not use adhesives which could dissolve in solvent washes ofthe coated surface.

It is still yet another object of the invention to provide a process forsampling semi-volatile organic compounds using the improved integratedvapor-particle sampler.

It is another object of the invention to provide a process for coating adenuder which minimizes displacement of the absorbent during transport,collection, and subsequent extraction for analysis.

It is still another object of the invention to provide a process forextraction of organic species from the coating of the annular denuder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the integrated vapor-particle sampler of theinvention with portions cut away, where three denuders are placed infront of the filter pack.

FIG. 2 is a side view of an alternate embodiment of the integratedvapor-particle sampler of the invention, with portions cut away, wheretwo denuders are placed in front of the filter pack and one denuder isplaced after the filter pack.

FIG. 3A is a cross-sectional view of a coated single-channel annulardenuder. FIG. 3B represents a section of the denuder seen in FIG. 3A.

FIG. 4 is a cross-sectional view of a multi-channel annular denuder.

FIG. 5 is a plan view of a multi-channel annular denuder.

FIG. 6 is a photo-micrograph showing the surface of an sandblasteduncoated glass denuder.

FIG. 7 is a photo-micrograph showing the surface of a sandblasted resincoated denuder of the invention.

FIG. 8 shows semi-logarithmic plots of napthalene (FIG. 8A),1-methylnaphtalene (FIG. 8B), fluorene (FIG. 8C) and phenanthrene (FIG.8D) gas-phase PAH as a function of denuder position for various flowrates and two sampling times.

FIG. 9 shows semi-logarithmic plots of outlet concentration to inletconcentration of napthalene (FIG. 9A), 1-methylnapthalene (FIG. 9B),fluorene (FIG. 9C) and phenanthrene (FIG. 9D), gas-phase PAHconcentrations as a function of length of denuder to volume of sampledair for various flow rates and two sampling times.

DEFINITIONS

As used herein:

“Integrated organic vapor-particle sampler (IOVPS)” means an apparatusable to quantitatively sample and separate semi-volatile organic gasesand particulate components.

“Macroreticular” means the unique structure of the polymers used in thepresent invention which are produced by a phase separation techniqueutilizing a precipitating agent.

“Microporosity” or “microreticularity” means molecular porositypresently known in the art as essentially homogenous crosslinked gelswherein the pore structure is defined by molecular-sized openingsbetween polymer chains.

“Macroreticular resins” means resins which contain significant non-gelporosity in addition to the normal gel porosity, where the non-gel poreshave been seen, by electron micrographs, to be channels betweenagglomerates of minute spherical gel particles, the prior art gel resinhaving a continuous polymeric phase while the macroreticular resinhaving agglomerates of randomly packed microspheres with a continuousnon-gel porous structure.

“Porous” as used herein refers to the channels or openings betweenagglomerates of minute spherical particles.

DETAILED DESCRIPTION OF THE INVENTION

The present invention concerns a quantitative organic vapor-particlesampler which can efficiently sample both semi-volatile organic gasesand particulate components through the use of a unique sorbent resincoating.

The invention further concerns a semi-volatile organic reversible gassorbent for use in an integrated diffusion vapor-particle samplercomprising macroreticular resin agglomerates of random packedmicrospheres with the continuous porous structure of particles rangingin size between 0.05-10 μm.

In addition to the resin coating, the invention concerns a process forsampling organic vapor/particle gas streams using the sampler of theinvention.

I. Integrated Organic Vapor Particle Samplers

A. Description of the Integrated Organic-Vapor Particle Sampler of theInstant Invention

The present invention involves a quantitative integrated organicvapor-particle sampler (IOVPS) comprising a new resin-coated annulardenuder and filter, which enable organic vapor/particle compositions tobe efficiently phase separated and quantitatively measured using aunique sorbent resin coating.

The sampler of the present invention comprises in its broadest aspect atubular device having an inlet at one end through which organic vaporand particles are introduced, an outlet at the other end through whichgases exit, at least one annular denuder interposed therebetween whichis coated on the inside surfaces of the annulus with a speciallyprepared resin absorbent which selectively absorbs organic vaporscontained in the gases introduced into the inlet, and a filter whichtraps and collects the particulate components.

The IOVPS of the present invention are designed to directly measuresemi-volatile organic species in both the gas-phase and particle-phase.Since lung deposition patterns of polycyclic aromatic hydrocarbons (PAH)depend on the distribution of PAH between the gas and particle phases,accurate measurements of phase distributions of PAH are needed in orderto assess exposure to carcinogenic compounds.

The IOVPS of the invention and its various individual components areseen in FIGS. 1-5. FIG. 1 shows one embodiment of the sampler of thepresent invention.

As shown in FIG. 1, the integrated organic vapor-particle sampler 10 ofthis invention comprises an elongated tubular device verticallypositioned having attached a cyclone component 12 at the lower end and afilter pack component 14 at the opposite and upper end. An inlet pipecomponent 16 is joined to the cyclone 12 by means of a coupler 18. Anoutlet tube 20 projects upward from the filter pack 14.

Positioned intermediate between the cyclone 12 and the filter pack 14 isa plurality of annular denuders 22, 24 and 26 connected to each other,and also to the cyclone 12 and to the filter pack 14 by means ofconnectors 28, 30, 32, and 34.

The cyclone 12 has an interior baffle arrangement 13 that allows largeparticles of particulate matter to fall to the floor while gaseouscomponents rise upward when the gas/particulate mixture enters thecyclone through the inlet pipe 16.

The filter pack component 14 comprises an annular support which holds aglass fiber or other type of filter mounted there.

The individual annular denuders 22, 24 and 26 connect to the connectors28, 30, 32 and 34 by means of threads on the ends of the denuders (notshown) engaging complementary threads on the connectors (not shown).Annuli of the denuders is coated with a resin.

FIG. 2 shows an alternate embodiment of the integrated organicvapor-particle sampler of FIG. 1.

The elongated tubular device 11 comprises two denuders 22 and 24, placedbetween the cyclone 12 and the filter pack 14 and one additional denuder27, placed between the filter pack 14 and the outlet tube 20.

The annular denuders 22, 24 and 27 are connected to each other, to thecyclone 12, the filter pack 14, and the outlet tube 20, by means ofconnectors 28, 30, 32 and 34 by means of threads on the ends thedenuders (not shown) engaging complementary threads on the connectors,cyclone 12, filter pack 14 and outlet tube 20 (not shown).

The annular denuder sections, shown as 22, 24, 26 and 27 in FIGS. 1 and2, are coated with ground sorbent particles. The ground sorbentparticles adsorb gases from the airstream. The filter pack is a holderfor one or more glass or quartz fabric filters which sieve the airborneparticles from the airstream. Couplers and fittings are used to connectthe components.

FIG. 3A is a cross-sectional view of a coated single-channel annulardenuder. FIG. 3B represents a section of the denuder seen in FIG. 3A.

As shown in FIG. 3A, the annular denuder 22 comprises an outer hollowcylindrical tube 36 and an inner cylindrical rod 38, the two rods havingthe same central axis, and the outer hollow cylindrical tube 36 beingconcentric with respect to the inner cylindrical tube 38.

The inner cylindrical rod 38 is inset 25 mm from one end of the outercylindrical tube 36. This end is called the flow straightener end. Theother end of the inner cylindrical tube 38 is flush with the other endof the outer cylindrical tube 36. Both ends of the inner cylindricaltube 38 are sealed.

The inner surface 40 of the outer hollow cylindrical tube 36 and theouter surface 42 of the inner cylindrical tube 38 define an annulustherebetween, of which surfaces are coated with a macroreticular resinof the invention described below, and through which annulus the organicvapor/particulate composition passes.

The tubes are connected to each other with small epoxy resin spacersplaced at each end of the tubes. The epoxy resin spacers separate thetubes, enabling the annulus to be defined therebetween.

The actual physical components of the denuder can be purchasedcommercially from University Research Glassware, 118 E. Main St.Carrboro, N.C. 27510. The improved sampler of this invention lies in theparticular resin applied to the inside surfaces of the denudercomponent.

B. Preferred and Alternate Embodiments

One alternate embodiment of the invention, for example, places a denuderor a sorben; bed after the filter pack to collect and measure blow-offfrom the particles caught on the filters. This embodiment of theintegrated organic vapor-particle sampler is shown in FIG. 2.

In the most preferred embodiment of the invention the integrated organicvapor-particle sampler (IOVPS), the denuder is formed of two concentrictubes 36 and 38 which define an annulus therebetween.

Yet another embodiment of the invention utilizes three or moreconcentric tubes with an annulus defined between each pair of adjacentconcentric tubes. A cross section of such a multi-channel denuderconsisting of four concentric glass tubes is shown in FIG. 4. FIG. 4 isthe cross-sectional view of a multi-channel denuder 43 consisting offour concentric glass tubes 44, 46, 48, 50. FIG. 5 shows (partially insection) the multi-channel denuder 43 of FIG. 4 in side view.

In still another embodiment of the invention the annulus of the annulardenuder is lined with polyurethane foam.

Still another embodiment of the IOVPS combines the coating of the IOVPSwith structural elements of Gas and Particle (GAP) samplers which aresimilar in design to the IOVPS, but have thirty times the surface area.The Gas and Particle samplers were designed for operation as differencedenuders for measurement of the phase distributions of pesticides inoutdoor air.

The IOVPS of the invention has been developed to use hardware that hasalready been validated for sampling of acid gases. The sampler geometryand flow characteristics have been thoroughly investigated. Theadvantages of sampling gas phase pollutants with annular diffusiondenuders have now been extended to organic species that are adsorbed bythe macroreticular resin XAD-4 and similar adsorbents.

The modular design of the IOVPS allows the configuration of itscomponents to be tailored for the needs of each investigation. Forexample, the total length of the denuder section can be adjusted bychoice of the number of denuders used, and different coating types couldbe used in the different pre-filter sections. The filter holder cancontain up to four filters if desired. The post-denuder section can be adenuder, sorbent bed or polyurethane foam collector.

From the foregoing, one skilled in the art can recognize that thepresent invention provides a new instrument for the quantitation ofgas-phase and particle-phase species of semi-volatile organic compounds.The foregoing disclosures and descriptions of the invention areillustrative and explanatory of the invention. Without furtherelaboration, it is believed that one of ordinary skill in the art can,using the preceding description, utilize the present invention to itsfullest extent.

Additional embodiments will be obvious to those skilled in the art ofthe present invention. Various materials may be used which meet therequirement of macroporosity discussed herein. A variety of denudergeometries may also be used which are functionally equivalent to thedenuder geometry illustrated herein. Alternative methods of preparingthe denuder with the advantageous coating described below may be used.

The IOVPS represents a significant improvement on conventionalfilter-sorbent bed samplers designed to sample gas-phase semi-volatileorganic compounds. It addresses the conventional samplers' inherentproblems, which include positive and negative artifacts and theinability to quantitatively recover gas-phase species. The IOVPS stripsthe gas-phase species from the air stream before particle collection bya filter. Although volatilization losses of semi-volatile species fromparticles are possible if the IOVPS is operated at a high face velocity,the IOVPS can be configured to correct for “blow-off” from the filters,by placing a denuder or sorbent bed downstream of the filter.

C. Assembly of the Integrated Organic Vapor-Particle Sampler (IOVPS)

The IOVPS has three primary elements: a size-selective inlet, annulardenuder sections, and a filter pack for one or more filters.

These components are shown in FIGS. 1 and 2 described in detail above.

The size-selective inlet, a Teflon-coated aluminum cyclone, whosefunction is to provide a 90°bend and orifice for separation of particlesgreater than 2.5 μm diameter from the sampled airstream was selected. Animpaction plate could also have been used, although the cyclone designis preferred for accurate separation of large particles from theairstream without contaminating the airstream with the grease which animpactor plate requires.

A selected plurality of annular denuder sections was coated with theground sorbent particles as described below. The coating adsorbs gasesfrom the airstream. After coating, the denuder sections were attached tothe cyclone and each other by means of connectors.

A filter pack containing one or more glass or quartz fabric filterswhich sieve the airborne particles from the airstream was then connectedto the last denuder by means of a connector.

Optionally, another ground sorbent coated denuder section may be addedafter the filter pack to collect any filter “blow-off” gases.

D. Samplers Used for Field Testing

The sampling configuration of IOVPS which was used for the field testingis seen in FIG. 1. commercially available single channel glass denuders,22 cm long, from University Research Glassware, Carrboro, N.C. were usedwith a Teflon-lined aluminum cyclone preceding the first denuder. Thecyclone was designed to remove particles with an aerodynamic diameter ofless than 2.5 micrometers. Three denuders were connected in seriesbetween the cyclone and a Teflon filter pack. Pre-extracted andpre-weighed Teflon-coated glass fiber filters were used. The sorbent bedsampler used an aluminum open-face filter holder with Teflon-coatedglass fiber filters followed by a glass tube packed with 2.5 g cleanedXAD-4 resin. Flow rates were measured with a dry gas test meter. Thisconfiguration was used to evaluate breakthrough and capacity asfunctions of flow rate and sampling time. The IOVPS sampled indoorlaboratory room air in these experiments. As the emphasis was onevaluation of its collection of gas-phase components, no sorbent ordenuder was usually used downstream of the filter.

The configuration used to sample environmental tobacco smoke (ETS) isseen in FIG. 2. Two denuders were used between the cyclone and filterpack, the third denuder followed the filter pack. Two filters were usedin the filter pack when sampling ETS. In one experiment thisconfiguration was also used to sample laboratory air. In thisconfiguration the whole phase distribution could be determined sincecorrection could be made for adsorption characteristics of the filterand for evaporation from particles.

II. Coating Resin and Its Preparation

One critical aspect of this invention is the inventive macroreticularresin which is used to coat the annulus of the denuder of the integratedorganic vapor-particle sampler of the instant invention.

A. Resin Materials

It has been found that gas phase polycyclic aromatic hydrocarbons (PAH)can be separated most efficiently from particulate matter andquantitative measurements made by using a macroreticular resin, such asdescribed in U.S. Pat. No. 4,224,415, incorporated by reference.

The macroreticular resin is the unique structure of the polymers used inthe present invention which are produced by a phase separation techniqueutilizing a precipitating agent. While conventional prior art resins areessentially homogeneous crosslinked gels where the only pore structureis defined by molecular-sized openings, also called microporosity ormicroreticularity, between polymer chains, macroreticular resins, bycontract, contain significant non-gel porosity in addition to the normalgel porosity.

The non-gel pores have been seen by electron-micrographs to be channelsbetween agglomerates of minute spherical gel particles. Themacroreticular resin of the invention is seen in FIG. 7. FIG. 6 is aphoto-micrograph showing the surface of a sandblasted uncoated glassdenuder. FIG. 7 is a photo-micrograph showing the surface of thesandblasted denuder coated with macroreticular resin of the invention.

The prior art gel resin has a continuous polymeric phase while themacroreticular resin is clearly shown to be agglomerates of randomlypacked microspheres with the continuous non-gel porous structure. Theterm porous refers to the channels or openings between agglomerates ofminute spherical particles.

The absorbent of the present invention preferentially comprises amacroreticular resin which is applied to the inside surface of theannulus after preparation in the manner described hereinafter.

The most preferred macroreticular resin is a styrene divinyl benzenecopolymer, commercially available from Rohm and Haas Corporation,Philadelphia, Pa., under the trade name XAD-4. XAD-4 is a macroreticularcross-linked aromatic polymer with a surface area of 780 m²/g and aporosity volume percentage of 45%. Its pore size ranges from 1-150 Å andits average pore diameter is 50 Å. XAD-4 density is 1.02 g/mL.

Other suitable resins of the same family include those sold under thetrade names XAD-2, XAD-16, Chromosorb 102, and Ostion SP-1. These, andother macroreticular resins suitable for use in the annular denuders,are set forth in Table 1.

TABLE 1 Macroreticular Resins Suitable for Use with the IOVPS CommonArea Pore Size Name Type (m²g) (Å) XAD-1 styrene-divinylbenzene (DVB)100 200 XAD-2 styrene-divinylbenzene (DVB) 350 90 XAD-4styrene-divinylbenzene (DVB) 780 50 Ostion SP-1 styrene-divinylbenzene(DVB) 350 85 Chromosorb 102 styrene-divinylbenzene (DVB) 350 90Chromosorb 105 polyaromatic polystyrene 650 500 Chromosorb 106polyaromatic polysterene 750 — Synachrom ethylvinylbenzene - DVB 570 45Porapak Q ethylvinylbenzene - DVB 735 — XAD-7 methylmethacrylate 450 80XAD-8 methylmethacrylate 140 250 Spheron MD methacrylate - DVB 320 —Spheron SE methacrylate-styrene 70 — Tenax - TA 2,6-diphenyl-p-phenyleneoxide 35 2000

Still other materials which can be used to coat the annulus of thedenuders include non-bonded silica, bonded silica, alumina, fluoracil,activated carbons and carbon black, and a porous polymer resin availablefrom many different sources, known under the trade name Tenax-TA.Tenax-TA, a 2,6-diphenyl-p-phenylene oxide resin, has a surface area of35 m²/g, an average pore size of 200 nanometers, and a density of 0.16g/cc. Its properties are described in the Alltech Chromatography catalog300, page 157 (1993), incorporated herein by reference. Tenax-TA may beobtained from Alltech Associates, Inc., 2051 Waukegan Road, Deerfield,Ill. 60015.

As stated above, the most preferred resin for coating of the surface ofthe annulus is XAD-4. This is a styrene-divinyl benzene resin having anarea of 780 m²/g and an average pore diameter of 50 Å.

Insofar as applicable for preparation of macroreticular resin of theinvention, certain techniques described in and the U.S. Pat. No.5,302,191 itself are hereby incorporated by reference.

B. Preparation of the Coating

The coating material was ground into fine particles before applicationto the sampling equipment. About 8 grams of macroreticular resin beadssuch as XAD-4, XAD-7, XAD-16, Tenax-GC, and various ion exchange beads,activated carbon particles such as Carbotrap and chromatographic-gradesilica were ground separately using a commercial centrifugal grinder.The grinder, a Fritsch Pulverisette, type 05.101, with an agatecontainer and agate balls, operated at speed 7 of 10, for between 6 and21 hours. The best grinding time depended on the nature of theparticles. The aim was reduction of average particle size to less than 1micrometer. XAD-4 which had been ground for six hours contained a fewbeads of unground resin which were removed from the batch before furtherprocessing. It was also possible to obtain suitable particles by using ahand-operated mortar and pestle to grind macroreticular resins. Thefinely-ground particles were separated from the remainder of the batchby forcing the mortar output through a several layers of fine stainlesssteel mesh.

C. Removal of Impurities and Very Fine Particles

The ground resin or other sorbent was extensively cleaned by solventextraction to remove impurities which, if not removed before airsampling, interfered with subsequent quantitative analysis of adsorbedspecies. After grinding, the particles were sonicated with 200 mLcyclohexane for 20 min. Aliquots (5 mL) of the suspension weretransferred to a vacuum filtration device loaded with an unlaminatedTeflon filter with nominal pore size of 0.5 micrometers and outerdiameter 47 mm (Millipore Corp., FHUP 0047). Vacuum was applied untilthe sorbent was almost dry, and then another aliquot of suspension wastransferred to the same device. The transfer and filtration wererepeated until half the slurry was transferred. Methanol was added intwo 25 mL aliquots. Vacuum was applied until the sorbent was dry enoughto crack. The filtration barrel was carefully removed, exposing theTeflon filter and cleaned sorbent which were then removed to a cleanwatch glass for air drying. The remainder of the cyclohexane slurry wastreated in the same way. Acceptable blank levels of the analytes ofinterest were found. Besides collecting the cleaned sorbent, thefiltration process removed sorbent particles smaller than the pore sizeof the filter which otherwise clogged capillary tubing in the analyticalinstrumentation whose use is described below. After the clean groundsorbent particles were dry they were carefully scraped off the filterinto a glass mortar and ground by hand for about one minute beforestorage in a stoppered glass bottle.

D. Properties of Resin Beads

The coating material is ground into fine particles before application tothe sampling equipment. Macroreticular resin beads and various ionexchange beads, activated carbon particles such as Carbotrap andchromatographic-grade silica are ground separately using a commercialcentrifugal grinder. The goal of the grinding is reduction of theaverage particle size to less than 1 μm. Remaining unground resin isremoved from the batch before further processing. It is also possible toobtain suitable particles by using a hand-operated mortar and pestle togrind macroreticular resins. The finely-ground particles are separatedfrom the remainder of the batch by forcing the mortar output throughseveral layers of fine stainless steel mesh.

Previously, when the diameters of a few unground XAD-4 particles weremeasured using an optical microscope, typical diameter of the particlewas 0.76 mm. When a larger sample was measured by placing ten beads endto end along a machinist's scale and noting the length, the averagediameter was 0.95 mm.

The unground beads of the commercially available resins are almost aslarge in diameter as the annular space of the IOVPS (1 mm) and wouldcause complete blockage of the annulus because both surfaces need to becoated. For denuders of larger annulus (up to 3 mm in the highercapacity IOVPS), the annulus would be reduced to 1 mm and the presenceof such a bumpy coating would induce turbulence in the gas flow.Turbulence would lead to particle deposition and the phase distributionmeasurements would be impossible to achieve.

Additionally, unground beads do not form a slurry, but adheretemporarily to a glass surfaces rod as long as the beads are wet with acompatible solvent such as hexane. They fall off as the solventevaporates. The behavior is similar for attachment to sandblastedsurfaces. Such large particles cannot be used as a denuder coatingbecause their ability to adhere is exceeded by their mass. Properties ofground and unground XAD resin particles are seen in Table 2.

Table 2 below shows the surface area and volume calculations forunground and ground particles and the effect of grinding on surface areaof a slurry.

TABLE 2 Surface Area and Volume Calculations for Ground and Unground XADResin Surface Area Volume Surface Ratio Diameter Diameter Radius cm² cm³Area/Volume ground/ μm cm cm 4πr² ({fraction (4/3)})πr³ cm⁻¹ ungroundunground 764 0.0764 0.0382 0.018337 0.000233 78.53 ground 0.753 7.53E−053.77E−05 1.78E−08 2.24E−13 79681 1015 Surface Surface Ratio DiameterDiameter Radius Area Volume Area/Volume ground/ μm m m m² m³ m⁻¹unground unground 764 0.000764 0.000382 1.83E−06 2.33E−10 7853 ground0.753 7.53E−07 3.77E−07 1.78E−12 2.24E−19 7968127 1015

The ground resin or other sorbent must be cleaned by solvent extractionto remove impurities which, if not removed before air sampling,interfere with subsequent quantitative analysis of adsorbed species. Theparticles are then sonicated and dried in a vacuum filtration deviceloaded with a filter with nominal pore size of 0.5 μm. Methanol is addedand vacuum reapplied until the sorbent is dry enough to crack. The cleansorbent is then removed to a clean watch glass for air drying.

This filtration process removes sorbent particles smaller than the poresize of the filter which otherwise clogs capillary tubing in theanalytical instrumentation.

The clean dry ground sorbent particles are next carefully scraped offthe filter into a glass mortar and ground by hand for about one minuteand then stored for future use.

E. Electron Microscopy

The coated and uncoated glass fragments were analyzed at the U.S.Environmental Protection Agency Scanning Electron Microscope Laboratoryin Research Triangle Park, North Carolina. The instrument was an AmrayModel 1000 scanning electron microscope, an analog instrument withmanual stage control and resolution of about 70 nm at 30 keV. Theinstrument was used at 20 keV, 50 μÅ beam, 26° tilt and 12 mm workingdistance. The samples were scanned at 500 and 2000 times magnification.Analysis of the particle size distribution of the XAD-4-coated fragmentfound that the coating was composed of particles with median and averagediameters of 0.7 and 0.9 μm, respectively. The geometric mean was 0.75μm, with a geometric standard deviation of 1.8 μm. The uncoated andcoated annular denuder surfaces, respectively, are seen in FIGS. 6 and7.

For testing, an annular denuder section (manufactured by URG) was takenfrom the laboratory's stockpile at random and intentionally shattered.Two small fragments were selected for electron microscopic analysis. One3 mm×3 mm fragment was coated by adding the fragment to 2 mL of a slurryof ground XAD-4 (30 mg in 200 mL hexane) and ultrasonicating for 5minutes. The fragment was removed with tweezers and dried on a cleanmicroscope slide in a nitrogen atmosphere for 5 minutes. The process wasrepeated for a total of four times. After the last coating, the surfacehad a visible thin coating of white powder which was not dislodged whenthe fragment was tapped gently. A similar uncoated fragment from thesame denuder was also selected for electron microscopy.

III. Coating of Integrated Organic Vapor-particle Sampler

A. Techniques Used for Denuder Coating

Typically, a sandblasted glass annular denuder section is capped at oneend, filled with spectral grade acetonitrile, capped at the other end,and cleaned by sonication. An ultrasonic bath large enough toaccommodate the whole length of the section is used. The cleaned sectionis dried by passing a low flow of clean nitrogen gas through it for afew minutes. The total mass of the clean uncapped denuder section isdetermined.

Slurries of the macroreticular resin are applied to the denuder. First,the slurry is sonicated briefly to assure suspension of the resin inhexane as some settling of the slurry may occur during storage. Thedenuder is then capped at one end and the slurry is poured into thedenuder. The other end of the denuder is capped and the denuder manuallyinverted about 10 times. The remaining slurry is drained from thedenuder into a beaker. The denuder is dried with a low flow of cleannitrogen for 30 to 60 seconds. The coated denuder is weighed again.

The coating, drying and weighing procedure of the denuder is repeated atleast ten times. After coating of the denuder is complete, hexane ispoured into the capped denuder which is then inverted a few times. Thehexane is drained out.

The glued areas of the glass in the denuder ends are sonicated in hexaneto remove any loose resin which might otherwise be blown off the gluesurface during sampling.

The net coating mass is determined by weighing the coated denudersection after the hexane rinse.

The coating technique produces a stable even coating which remains inplace during sampling even at 20 L/min for 24 hours. However, the capsand connectors must be free of XAD-4 powder before they are attached tothe coated denuders. Dry powder from the caps or connectors may lead todeposits of XAD-4 on the afterfilter. This would lead to erroneousresults.

Sandblasted glass surfaces of any geometry can be coated by adapting thetechnique described above. For example, the suspended slurry of sorbentin solvent can be poured over a flat surface; a tube can be filled withthe slurry, or the slurry can be poured through while the tube isrotated by hand or motor. A rod can be dipped into the slurry while itis suspended in a beaker or graduated cylinder.

The integrated organic vapor-particle samplers are inserted in thechamber to be tested. The ventilation ducts and chamber doors are sealedshut with duct tape during the experiment to minimize the air exchangerate and improve the accuracy of the results of the analysis.

The integrated organic vapor-samplers are then removed in sequence.

For studies performed in development of this invention, sandblastedglass annular denuder sections 22, 24 and 26, seen in FIG. 1, werepurchased from University Research Glass, Carrboro, N.C., part numberURG 2000-30B, 220 mm length. They were capped at one end withTeflon-lined caps, filled with spectral grade acetonitrile, capped atthe other end, and cleaned by sonication for 20 minutes. An ultrasonicbath large enough to accommodate the whole length of a section was used.The cleaned sections were dried by passing a low flow of clean nitrogengas through them for a few minutes. The total mass of the clean uncappeddenuder was determined using a Mettler balance, Model H35AR (to 0.0001g). Slurries of density 50, 100, 200 and 250 mg ground XAD-4 in 30 mLhexane were prepared and used to test the coating procedure.

Each slurry was applied in the same way. First, the slurry was sonicatedbriefly to assure suspension of the resin in hexane. Some settling ofthe XAD-4 was observed for a slurry density of 250 mg/30 mL hexane. Thenthe slurry was poured into the denuder which had been capped at one end.Then the other end was capped and the denuder manually inverted about 10times. The remaining slurry was drained into a beaker from the denuder.

The denuder was dried with a low flow of clean nitrogen for 30 to 60sec. The coated denuder was weighed again. The coating, drying andweighing procedure was repeated at least ten times. After coating wascomplete, hexane was poured into the capped denuder which was theninverted a few times. The hexane was drained out, and each end wassonicated in hexane just covering the glued areas of the glass. Thehexane rinse removed any loose XAD-4 which might otherwise be blown offthe glass surface during sampling. The net coating mass was determinedby weighing the coated section after the hexane rinse.

The results showed that the greater the slurry density, the more quicklythe denuder gained mass, but the maximum coating remained the sameregardless of the slurry density. Use of slurries of greater than 500mg/30 mL hexane led to streaky coating. However, the net coating masswas typically 10-20 mg. for clean single-annulus denuder sections of 22cm length which had previously been stripped of the XAD-4 by sonicationin acetonitrile. Ethyl acetate removed XAD-4 even more thoroughly thanacetonitrile. The net coating mass was reproducible to +1 mg forindividual denuders. Based on the results described, a slurry density of200 mg/30 mL hexane was chosen for routine coating procedures.

B. Preparation of Multi-channel Annular Denuders

The IOVPS may have one, but has preferably multiplicity of denuders.

The coating technique was applied to 5-channel annular denuder sections(URG-2000-30x; sandblasted length 125 and 220 mm) whose interiorsurfaces had been sandblasted in the same manner as the single channeldenuder sections. When ground XAD-4 was used as the sorbent, the netcoating mass was about three times that found for a single-channeldenuder of the same coated length. That result is consistent with themeasured difference in surface area between the single and five-channelannular denuder sections of similar sandblasted lengths.

C. High Capacity IOVPS

Gas and Particle (GAP) samplers are similar in design to the IOVPS, butthe GAP samplers have thirty times the surface area. They were designedfor operation as difference denuders for measurement of the phasedistributions of pesticides in outdoor air.

An embodiment of the IOVPS which combines the coating of the IOVPS withstructural elements of GAP samplers was prepared as follows. Theadsorbent coating, crushed Tenax particles imbedded in silicone gum, wasremoved from the glass denuder sections of two GAP samplers by rinsingthe inside of the denuder section with dichloromethane. The sixconcentric tubes were disassembled, and sections 55 cm in length weresandblasted on the inside and outside with silicon carbide particles ofmesh size 320.

The denuders were next cleaned in acetonitrile and hexane and thencoated with ground XAD-4 using procedures based on those describedabove. The tubes were carefully reinstalled into the outer shell of theGAP denuder. A slurry of 3.2 g ground XAD-4 in 490 mL hexane wassonicated for 10 minutes and poured into the reassembled denuder sectionafter one end had been capped. After capping the other end, the denuderwas rotated along its axis and from end to end for ten times in eachdirection. The slurry was poured out, collected, sonicated again for 5min, and then the coating step was repeated twice. Following a hexanerinse to remove fine particles, the coated GAP denuder section was driedwith a stream of dry nitrogen gas. The caps were reapplied, and thedenuder was stored at room temperature until the field test.

D. Coating Versus Sand Grit Size on Coated Glass Disks

Six pre-weighed Pyrex glass discs of 3.9 cm diameter were ground on oneside with a range of Carborundum (silicon carbide) particles with gritsizes 80, 150, 240, 320, 400 and 600. After cleaning by sonication withacetonitrile each disc was coated with XAD-4 using a modification of theprocedures disclosed in the application. Because the discs were flat,the suspension was poured over three of them as they lay flat, groundside up, in a watch glass before the slurry was sloshed around over thediscs ten times for good contact. Each disc was rinsed ten times withhexane to remove unattached particles. Any powder on the smooth back ofthe disk or edge was removed by wiping before mass determination. Thenet coating mass and coverage data are presented in Table 3.

TABLE 3 Coating v. Sand Grit Size for Coatings on Selected Glass DiscsNet mass Coverage Track width Grit size mg mg/cm² micrometer 80 0.3 0.02150 0.3 0.02 240 0.1 0.01 70 320 0.4 0.03 50 400 0.2 0.01 40 600 0.30.02 20

D. Evaluation of Coating Stability on the Denuders

The coating stability was evaluated from the post-denuder filter inthree ways: a) by visual examination, b) by mass determination, and c)by evaluation of the PAH concentration distribution for the particleextract.

After introduction of the final hexane rinse to the coating procedurethere was routinely no detectable deposition of XAD-4 on thepost-denuder. Filter- and filter loading and extract PAH distributionwere similar for filters from both the sorbent and denuder samplingtrains. The coating was stable during sampling at flow rates up to 20L/min, as assessed by visual inspection of black after filters that wereused for 24 hours of pump operation. Inspection of Teflon filters thathad been used to filter denuder extracts showed that the coating was notremoved by static solvent extraction, using two rinses of theintra-annular space, at 45° C. When observed, deposition of ground XADon the post-denuder filter during sampling appeared as higher thanexpected filter mass and higher than expected semi-volatile PAHconcentrations in the filter extracts.

IV. Process of Sampling Semi-Volatile Organic Compounds

Apparatus assembly, resin preparation and purification, denuder coatingsand sample preparations are as described above or below.

A. Laboratory IOVPS Emulation

The IOVPS was evaluated by sampling indoor laboratory air at roomtemperature (about 21° C.). The room was free of indoor combustionsources, and therefore the air represented outdoor air that had beenbrought into the building by the ventilation system. Sampling was doneat 5, 10 and 20 L/min for 3 and 6 hours, using three single-channelannular denuders in the configuration 0.075 seconds, respectively.Filter face velocities were 8, 17 and 33 cm/sec, respectively. Oneexperiment was done at 20 L/min for 22 hours. Separate clean componentswere used for each condition. The exposed denuders were refrigeratedbefore analysis if the extraction could not be carried out immediately.The filters were stored in the freezer before analysis.

Parallel sampling was done using a filter followed by a sorbent bedfilled with 2.5 g unground XAD-4 resin beads. The filter-sorbent samplerwas similar to that described by Loiselle et at., Indoor Air, 2:191-210(1991), except that the filter holder was stainless steel, and the flowrate was 20 L/min. The XAD-4 resin had been cleaned by sequentialSoxhlet extraction in dichloromethane and methanol. After heating in N₂at 40° C. in a fluidized bed for four hours the resin was stored in asealed bottle until use.

B. Sampling Conditions

The optimal sampling conditions for indoor air without environmentaltobacco smoke were chosen by consideration of the data obtained atvarious flow rates and sampling times. This was done by a) determiningthe observed concentrations of all detected PAH in each denuder section;b) determining the percentages of naphthalene and its methylderivatives, fluorene and phenanthrene that were trapped on the first ofthree denuders; and c) selecting conditions for which the first denudercollected at least 90% of the most volatile species, namely the threenaphthalenes. Compounds that are less volatile than the naphthaleneswere trapped at greater than 90% efficiency under those conditions.

C. Sample Extraction

The IOVPS is disassembled into its components. The open ends of eachdenuder are sealed with Teflon-lined screw caps and the denuders arethen stored in a refrigerator until analysis. The filters are removedfrom the filter pack, and stored in plastic petri dishes or othersuitable sealed containers in a freezer (−20° C.) until analysis.

At the time of extraction the denuders and filters are warmed to roomtemperature before extraction of the analytes. The annulus of eachdenuder is filled with an appropriate solvent and recapped after theaddition of an appropriate internal standard for recovery.

The denuders are sonicated or subject to static, microwave or Soxhletextraction for the time necessary to dissolve the analytes in theextraction solvent. Supercritical fluid extraction may also be used. Theextract is separated from any loose sorbent particles by filtration. Theextract is reduced in volume and the analytes determined by theappropriate analytical method.

The filters are extracted by contact with the appropriate solvent usingsonication, microwave, Soxhlet or supercritical fluid extraction.

D. Analysis of Extracts

For analysis of polycyclic aromatic hydrocarbons, the extraction solventwas cyclohexane. The extracts were passed through Teflon filters(unlaminated, Millipore Corp.) and then silica solid-phase extractioncolumns (packed in glass). Before analysis the solvent was exchanged toacetonitrile by evaporating the cleaned cyclohexane extracts on silicacolumns (200 mg) at room temperature and eluting with acetonitrile.Final sample volume was between 250 and 1000 μl. The injection volumefor high pressure liquid chromatographic (HPLC) analysis was 5 μL. Twounexposed coated denuders and pre-extracted filters were analyzed asblanks for every field test.

The extracts are passed through Teflon filters and the silicasolid-phase extraction columns packed in glass. Before analysis, thesolvent is exchanged to acetonitrile by evaporating the cleanedcyclohexane extracts on silica columns (200 mg) at room temperature andeluting with acetonitrile.

Extracts of the denuders are analyzed for PAH by adapting thedual-fluorescence technique developed by Mahanama et al. for analysis ofsemi-volatile PAH from naphthalene to chrysene Intern. J. Environ. Anal.Chem., 56:289 (1994).

A Hewlett-Packard high performance liquid chromatograph Model 1090 M wasused with a Vydac 201TP5215 column. The gradient program increased theeluant strength from 38% acetonitrile, 2% THF in water, to 95%acetonitrile, 5% THF, over 24 min at 0.5 mL/min. From 25 to 33 minutesthe flow increased linearly to 1 mL/min. After 4.5 min the flow ratereturned to 0.5 mL/min, and the mobile phase composition returned to theinitial condition during the next two minutes. A 12-minute equilibrationat 0.5 mL/min followed. The column was maintained at 30.8° C.

Each fluorescence detector is independently programmed to changeexcitation and emission wavelengths to selectively detect the PAH ofinterest as they elute from the column. One detector started atexcitation and emission wavelengths of 220 and 348 nm, respectively, todetect naphthalene and its 1- and 2-methyl derivatives, acenaphthene andacenaphthylene. At 11.5 minutes it is switched to 263 and 371 nm todetect chrysene. The second detector started at 246 and 296 nm to detectbiphenyl and fluorene; at 11.95 minutes it switched to 245 and 359 nm todetect phenanthrene; at 16 minutes it switched to 245 and 391 nm todetect pyrene; and at 21.7 minutes it changed to 288 and 405 nm todetect benz(a)anthracene. These fluorescence programs were developed bystudying the excitation and emission spectra of standard compounds toselect conditions of both high sensitivity and selectivity. However,during the field testing with environmental tobacco smoke severalmodifications were made, as described above, to overcome real-worldinterferences from other PAH and their alkyl derivatives. The detectionand quantitation limits for both the gas and particle phases, derivedfrom analysis of blanks, are shown in Table 4. Recovery of both internalstandards from denuder extracts averaged 70%. PAH concentration datawere corrected for the observed recovery. Extracts of filters wereanalyzed for PAH using the dual-fluorescence detector technique ofMahanama, ibid (1994).

TABLE 4 Detection and Quantitation Limits for Semi-Volatile PAH LLD(a)LLQ(b) LD(a, c) LLQ(b, c) PAH ng ng ng/m³ ng/m³ Gas phase Naphthalene 1344 43 130 1-Methylnaphthalene 4.8 16 16 48 2-Methylnaphthalene 19 62 63190 Biphenyl 31 105 105 315 Acenaphthene & 1.6 5.5 5.3 16 acenaphthyleneFluorene 2.9 9.7 9.7 29 Phenanthrene 6.4 21 21 64 Anthracene 0.06 0.190.2 0.6 Fluoranthene 0.5 1.7 1.7 5.0 Pyrene 0.5 1.7 1.7 5.0 Benz (a)anthracene 0.03 0.1 0.1 0.3 Chrysene 0.22 0.7 0.7 2.2 Particulate phaseNaphthalene 5.2 18 17 52 1-Methylnaphthalene 3.5 12 12 352-Methylnaphthalene 3.1 10 10 31 Biphenyl 0.74 2.2 2.5 7.4 Acenaphthene& 0.42 1.4 1.4 4.2 acenaphthylene Fluorene 0.37 1.2 1.2 3.7 Phenanthrene1.6 5.2 5.2 16 Anthracene 0.04 0.1 0.1 0.4 Fluoranthene 1.3 4.5 4.5 13Pyrene 0.42 1.4 1.4 4.2 Benz (a) anthracene 0.015 0.05 0.1 0.2 Chrysene0.32 1.1 1.1 3.2 (a) The lower limit of detection (LLD) is estimated as3 × the standard deviation observed for the blanks. (b) The lower limitof quantitation (LLQ) is estimated as 10 × the standard deviationobserved for the blanks (c) LLD and LLQ for 0.3 m³ air sample (1 hoursampling at 5 L/min).

E. Comparison to Filter-Sorbent Bed Sampling

Conventional samplers were constructed with a 47-mm diameter filterfollowed by a sorbent trap that contained between 0.15 and 2.5 cleanedunground XAD-4 resin beads (20-60 mesh). In several experiments thefilter-sorbent bed sampler was co-located indoors with the IOVPS andoperated for the same time and at the same flow rate. Because the twosampler types could yield different phase distributions of all but themost volatile PAH (due to the possibility of both positive and negativeartifacts expected from the conventional sampler), only species morevolatile than phenanthrene, i.e., the naphthalenes, acenaphthene,acenaphthylene and fluorene would be expected to be trapped with thesame efficiency by both sampler types. Gas phase concentrations of thesePAH were determined from the co-located samplers.

Data from sampling indoor laboratory room air at 20 L/min for 3 hoursare presented in Table 5.

TABLE 5 Comparison of IOVPS to Sorbent Bed for Collection of Gas PhasePAH (a) LLD for Denuder Sorbent Den/Sorb Den(b) PAH ng/m³ ng/m³ rationg/m³ Napthalene 545 798 0.68 2.9 l-Methylnaphthalene 161 202 0.80 0.72-Methylnaphthalene 220 315 0.70 1.5 Biphenyl 61.6 102 0.60 3.2Acenaphthene and 18.3 25.4 0.72 0.1 Acenaphthylene Fluorene 17.0 19.90.85 0.5 Phenanthrene 38.4 41.5 0.93 1.9 Anthracene 0.61 0.64 0.95 0.11Fluoranthene 6.06 7.25 0.84 0.74 Pyrene 2.33 2.98 0.78 0.68 Chrysene2.01 3.34 0.60 0.92 Average (Naph - Fluorene) 0.73 Average (Phen - Chry)0.82 (a) Indoor laboratory room air sampled at 20 L/min for 3 hours; airvolume = 3.7 m³. (b) The LLD was calculated from the observedvariability of two unused denuders.

The PAH concentrations observed in this experiment were the highestindoor concentrations encountered in this study, and the capacity of theIOVPS in the configuration shown in FIG. 1 was exceeded for the mostvolatile species. The IOVPS-derived PAH concentrations averaged 73±9% ofthe sorbent-derived concentrations for PAH more volatile thanphenanthrene, namely the naphthalenes, acenaphthylene, biphenyl andfluorene. The observed differences in concentrations of the naphthalenesare consistent with a deficit of about 25% in collection of thenaphthalenes by the IOVPS at 20 L/min that can be deduced from the dataof FIG. 8. Since the IOVPS was operated at a flow rate above its optimalsetting, incomplete trapping and/or losses of the most volatile specieswere not unexpected and are consistent with the results presented inTable 3 and FIG. 8. Denuder-derived concentrations for phenanthrene andthe less volatile PAH from the IOVPS averaged 82±14% of thesorbent-derived values for the same experiment. However, phenanthreneand less volatile species may show “blow-off” artifacts that increaseapparent sorbent bed concentration. Since the data presented in FIG. 8indicate that phenanthrene was collected in the three denuders withgreater than 90% efficiency even under the sampling conditions of thisexperiment, and since the denuders have higher efficiency for the lessvolatile PAH, the lower gas-phase concentrations measured with thedenuder for fluoranthene, pyrene, and chrysene are consistent with“blow-off” artifact from the particle-loaded filter in thefilter-sorbent bed sampler.

The available data indicate the IOVPS traps and recovers semi-volatilePAH quantitatively when its capacity is not exceeded. This conclusion isconsistent with the results obtained by other workers who are evaluatingthe IOVPS in chamber studies of PAH reactions in the presence ofcombustion effluents. Fan et al, presentation at the InternationalSymposium on Toxic and Related Air Pollutants, Durham, N.C. (1993)subsequently published in Atmospheric Environment, 29:1171 (1995), foundthat the concentrations of the naphthalenes, sampled at 20 L/min for 20minutes, obtained with the IOVPS agreed with those seen in afilter-sorbent bed sampler that used polyurethane foam as the trappingagent for gas-phase PAH.

V. Efficiency and Capacity of the Samplers

A. Performance of the Integrated Organic Vapor-Particle Sampler of theInvention

The efficiency of a sorbent-based sampler according to the inventiondepends on the concentrations of the sorbed species in the airstream. Atlow concentrations the volumetric capacity depends on the total volumeof air sampled and is independent of the gas-phase concentrations of thesorbed species. The holding power or efficiency of the trap is limitedby the amount of air necessary to elute or displace adsorbed materialfrom the surface, as occurs in gas-solid chromatography. At higher inletgas-phase concentrations the adsorption sites could be filled before thevolumetric capacity is exceeded because the weight capacity of thesorbent has been reached. The gas-phase PAH concentration data obtainedfrom sampling indoor air under various conditions have been used toestimate these limits for the IOVPS. The aim of these studies was tofind useful operating range rather than investigating the sorptionmechanism in detail.

For efficiency and capacity determinations, it was assumed that thevolumetric capacity Vg for a particular PAH had been exceeded for totalair volumes for which the first denuder collected less than 90% of thatPAH. The concentrations of all PAH were determined separately in eachdenuder section. The percentages of naphthalene and its methylderivatives, fluorene and phenanthrene found on the first of the threeserial denuders are shown in Table 6.

Table 6 presents the percentage recoveries on the first of threedenuders in series for naphthalene with its methyl derivatives, fluoreneand phenanthrene in series versus flow rate and sampling duration.

TABLE 6 Percent Recovery of PAH on the First of Three Denuders Samplingtime Flow rate, L/min hours 5 10 20 Naphthalene 3 99 93 44 6 93 88 42Fluorene 3 100 96 75 6 93 78 71 Phenanthrene 3 100 97 81 6 89 91 77 (a)Based on sampling indoor laboratory room air. Total gas - phase PAHconcentration was the sum of concentrations on three denuders in series.

The total PAH concentration was assumed to be the sum of the amountsfound on each denuder. This assumption may have underestimatednaphthalene concentrations for sampling at 20 L/min based on the datashown in FIG. 8, described below. Based on this data, eachsingle-channel denuder section of 22 mm length, as described above, maybe advantageously used upstream of the filter to sample up to 1.8 m³indoor air, equivalent to 10 L/min for 3 hours or 5 L/min for 6 hours.Therefore, quantitative collection of naphthalene and othersemi-volatile PAH from 3.6 m³ can be done with two denuders in series at10 L/min for 6 hours or at 20 L/min for 3 hours. Alternatively, a single5-channel denuder with 22 cm length could be used to sample up to atotal volume of 5.4 m³, but some particle loss may occur. Asingle-channel denuder of increased length could also be used toincrease trapping capacity. Results seen in FIG. 8 suggest that fourdenuder sections would trap at least 95% of fluorene, phenanthrene, andless volatile species at 20 L/min during 6 hours of sampling.

FIG. 8 shows semi-logarithmic plots of several gas-phase PAH as afunction of denuder position, for various flow rates and two samplingtimes. Specifically, FIG. 8 shows semi-logarithmic plots of PAHconcentration data for naphthalene, 1-methylnaphthalene, fluorene andphenanthrene versus denuder position in the sampling train.

Positions 1, 2 and 3 correspond to 22, 24 and 26 in FIG. 1. FIG. 8designators represent flow rates as follows: open squares: 20 L/min, 3hr; closed squares: 20 L/min, 6 hr; open diamonds: 10 L/min, 3 hr;closed diamonds: 10 L/min, 6 hr; open triangles: 5 L/min, 3 hr; andclosed triangles 5 L/min, 6 hr.

The solid line shows trapping of 90% of each PAH on the first (upstream)denuder wherein (a) is naphthalene; (b) is 1-methylnaphthalene; (c)fluorene and (d) is phenanthrene.

Position 1 refers to the denuder closest to the cyclone. Data for eachexperiment were normalized so that the amount of each PAH on the firstdenuder was 100 arbitrary units.

The data for 2-methyl naphthalene were between those for naphthalene and1-methylnaphthalene. The naphthalenes were not trapped as effectively at20 L/min as at 10 and 5 L/min. At 10 L/min logarithms of theconcentrations of the naphthalenes on each section were linear withdenuder position indicating exponential decay of gas-streamconcentrations. No naphthalenes were detected on the third denudersection when the flow rate was 5 L/min. Fluorene and phenanthrene werecollected on the third denuder only at 20 L/min, at which flow ratetheir concentration dependence also appeared to be exponential. Fluoreneand phenanthrene were not detected on the second denuder for sampling at10 L/min for 3 hours or for either sampling duration at 5 L/min. Eachsection of the figure has a line drawn to indicate 90% recovery of eachspecies on the first denuder for assumed exponential decrease of gasstream concentration versus denuder position.

As seen in FIG. 8, the method has a good reproducibility and the fourdenuder IOVPS was able to trap more than 95% of PAH.

Based on the results presented above it may be concluded that theoptimal flow rates for routine operation of the IOVPS, when it isassembled with single channel denuders of the diameter use here, are5-10 L/min. Optimal sampling time will depend on the concentration rangeexpected, the denuder coating mass and total length of the pre-filtersection. In these studies 3 hours were sufficient to trap PAH in indoorlaboratory room air at 5 and 10 L/min. Two pre-filter denuders should beused when capacity limits for a single denuder may be exceeded. Samplingat 20 L/min with three or four denuders in series can also be used whennaphthalene is not of interest. At this higher flow rate, a largersample of particles is collected, and lower limits of detection resultfor both particulate and gas phase PAH.

Volumetric capacity (Vg) is about 2 m³ per denuder section for thesecompounds. The data indicate that Vg is somewhat higher for sampling at10 L/min for 3 hours, compared to sampling, at 5 L/min for 6 hours.Apparently greater displacement or elution of PAH occurred at thecombination of lower flow rate (longer residence time) and longer totalsampling time. This result suggests that volumetric capacity depends onface velocity.

Lower limits to the weight capacity of the ground XAD-4 for several PAHwere estimated from the amounts of these compounds collected on thefirst and sometimes second of three denuders in series under conditionswhere breakthrough was observed. The XAD-4 coating mass was measured foreach denuder section. For the purposes of the estimate, breakthrough wasassumed to have occurred when the amount trapped on the next downstreamdenuder was more than 10% of the total found on all three denudersections. Based on this operational definition, breakthrough ofnaphthalene onto the second denuder was seen at 20 L/min for 3 hours ofsampling and at 10 L/min for 6 hours of sampling.

Breakthrough of naphthalene from the second denuder to the third denudersection occurred when the IOVPS operated at 20 L/min for 6 and 22 hours.Under those conditions naphthalene migrated axially along the denudersections during the extended sampling period, so the volumetric capacitywas exceeded. Breakthrough was not observed at 20 L/min for four-ringPAH. For the other PAH, breakthrough occurred only when sampling at 20L/min for 3 hours or longer. The observed breakthrough shows thatmigration along the denuder sections dominated the collection efficiencyfor the most volatile species, even though their higher diffusivitiescompared to the heavier PAH would predict more efficient collection in adiffusion denuder.

The weight capacity of ground XAD-4 for naphthalene, fluorene andphenanthrene, sampled together with other PAH, in indoor air was foundto be (±standard deviation; n=the number of observations) 57±16(n=8), >4.3+1.3 (n=3), and >7.7±3.4 (n=5) ng/mg XAD-4, respectively. Thehigh standard deviations reflect the fact that some of the denuders weretoo long to fit within the weighing compartment of the analyticalbalance and had to be weighed on a pan balance to the nearest 10 mg.Therefore, the coating mass was known only to only one significantfigure in those cases. The value found here for naphthalene is about 3times higher than estimated from breakthrough experiments for an XAD-4resin sorbent sampler. A typical denuder section can trap about 800 ngnaphthalene, 50 ng fluorene and 100 ng phenanthrene.

B. Assessment of TOVPS Performance

The performance of the IOVPS is assessed by using the models for annulardenuder efficiency developed by Possanzini et al., and described inAtmospheric Environment, 16:845-853, (1983) and Coutant, et al., Atmos.Environ., 23:2205 (1989). The Possanzini model applies to a surfacecoating that irreversibly reacts with the gas-phase component ofinterest. Coutant considers denuder performance when the reaction oradsorption probability is less than one for each collision of thegas-phase component with the denuder coating. Both models predict that,for sufficient denuder length, the ratio of outlet to inletconcentration for a trapped component of the airstream follows anexponential dependence on the ratio of denuder length to the total airflow.

For a single denuder section of length L the outlet concentration(C_(out)) of the gas phase component has been reduced from the inletconcentration (C_(in)) of the gas phase component by the amount of thegas phase component trapped on the denuder surface, per unit volume ofair. The efficiency is 1−(C_(out)/C_(in)).

For an IOVPS with several denuders the efficiency of the first sectionE₁ can be approximated by assuming that C_(in) is the sum of the amountsof gas phase component per m³ found on each section C₁, C₂, . . . C_(n),where n is the number of denuder sections. The outlet concentrationafter the first section is the difference between C_(in) and C₁.Therefore, the efficiency of one section is $\begin{matrix}{E_{1} = {{1 - \frac{C_{out}}{C_{in}}} = \frac{C_{1}}{C_{in}}}} & (1)\end{matrix}$

and the efficiency of two sections (used together) is $\begin{matrix}{E_{2} = \frac{C_{1} + C_{2}}{C_{in}}} & (2)\end{matrix}$

Practical use of these models for efficiency measurements is illustratedin FIG. 9.

FIG. 9 shows semi-logarithmic plots of outlet concentration C_(out) toinlet concentration C_(in) several gas-phase PAH concentrations as afunction of denuder length to the volume of sampled air, for variousflow rates and two sampling times.

The solid line shows trapping of 90% of each PAH on the inletconcentration for each denuder represent: (a) naphthalene; (b)1-methylnaphthalene; (c) fluorene; and (d) phenanthrene.

FIG. 9 designators are as follows: downward triangles, 5 L/min, 3 hr;upward triangles, 5 L/min, 6 hr; open squares: 10 L/min, 3 hr; opendiamonds: 10 L/min, 6 hr; open horizontal hexagons: 20 L/min, 3 hr; andopen vertical hexagons: 20 L/min, 6 hr. For naphthalene andmethylnaphthalene sampled at 20 L/min, C_(in) was taken from thefilter-sorbent bed sampler data.

FIG. 9 shows semi-logarithmic plots of C_(out)/C_(in) for collection ofseveral PAH versus the ratio of denuder length to the volume or air thatpassed through the IOVPS. The solid and open symbols correspond to thelength of one and two sections, respectively. For one section,C_(out)/C_(in)=(C_(in)−C₁)/C_(in). The solid symbols show(C_(in)−C₁)/C_(in) versus L1/V, where L1 is the length of the firstsection and V is the total volume of air sampled. The open symbols givethe data for two sections: C_(in)−[(C₁+C₂)/C_(in)], versus (L1+L2)/V.Data are shown for naphthalene, 1-methylnaphthalene, fluorene andphenanthrene samples in indoor air at flow rates of 5, 10, and 20 L/minfor 3 and 6 hours. C_(in) for 20 L/min includes the difference betweenamounts found on the denuder and parallel sorbent bed samples, i.e., theamounts not trapped by the three denuder sections of the IOVPS. The linedrawn in each section of the figure corresponds to the predictedexponential decay for a theoretical efficiency of 90% for each sectionwhen the IOVPS operates at 10 L/min for 3 hours sampling (or 5 L/min for6 hours). The ordinate value of 0.1 corresponds to 90% efficiency.

Besides confirming the volumetric gas capacity of 2 m³ per denudersection for 90% efficiency, the data suggest that C_(out)/C_(in) is anexponentially decaying function of the ratio of denuder length to airvolume, consistent with the models of Possanzini and Coutant. Efficiencyimproved as the molecular weight increased from naphthalene to fluorenewhile the vapor pressure decreased. For naphthalene, besides diffusionand adsorption, axial migration also influenced the collectionefficiency for sampling at 20 L/min.

C. Design Criteria for IOVPS

A spreadsheet template has been created for calculation of thetheoretical efficiency of an annular denuder with dimensions of GAPsample using the Possanzini equation, where:

CO=initial gas-phase concentration;

C=gas-phase concentration after passage through the denuder with annulusd₂−d₁;

d₁=inner diameter of the annulus in cm;

d₂=outer diameter of the annulus in cm²/sec;

D=the diffusion constant of the adsorbed species, in cm²/sec;

L=length of the coated section;

F=flow rate in cm³/sec;

The efficiency according to this calculation is defined as:

E=100(1−C/C_(O)) where

C/Co=0.82 exp (−22.53 delta_(a)); and

delta_(a)=pi D L (d₁+d₂)/[4F(d₁−d₂)].

An example spreadsheet for the hybrid IOVPS-GAP sampler appears in Table7, given below. Table 7 represents an efficiency calculation fornaphthalene, which has D=0.081 cm²/sec at room temperature.

TABLE 7 Naphthalene at Room Temperature Inside Inside Outside OutsideFlow N_(Ra) Std C/C_(o) Sect. Flow Annulus Diam. Area Diam. Area WidthArea Volume Cross Annulus Deviat. Flow (cm) (cm²) (cm) (cm²) (cm) (cm²)(cm³) Annulus (L/min) % Total (cm³/s) (%) (a) 0.20 34.56 0.60 103.670.20 0.25 15.08 0.35 5.86 2.10 61.33 1.19 1.669E−1 (b) 0.80 138.23 1.26217.71 0.23 0.74 44.65 1.04 17.34 6.23 70.52 0.90 1.184E−09 (c) 1.50259.18 1.90 328.30 0.20 1.07 64.09 1.49 24.89 8.94 61.33 1.19 1.669E−12(d) 2.20 380.13 2.64 456.16 0.22 1.67 100.36 2.34 38.98 14.00 67.46 0.991.784E−10 (e) 3.00 518.36 3.40 587.48 0.20 2.01 120.64 2.81 46.85 16.8361.33 1.19 1.669E−12 (f) 3.80 656.59 4.40 760.26 0.30 3.86 231.85 5.4090.05 32.35 91.99 0.53 5.216E−06 (g) 4.80 829.38 5.10 881.22 0.15 2.33139.96 3.26 54.36 19.53 45.99 2.12 1.347E− 21 2816.44 3334.80 11.94716.62 16.70 278.33 100.00 C = initial concentration C_(o) =concentration after denuder D = diffusion coefficient in cm²/sec L =coating length in cm F = flow rate in the tube/annulus (cm³/sec)

Spreadsheets of this type have been used for prediction of thecollection efficiency of denuders of various dimensions. The theoreticalefficiencies assume perfect retention of the species of interest such asoccurs for the chemical reaction of HONO at a denuder surface coatedwith sodium carbonate. The actual efficiency of a denuder that traps byadsorption will be reduced by a factor that must be determinedexperimentally.

VI. Laboratory and Field Testing

Assembly of the equipment used for field testing is described in SectionI. Coating was prepared and impurities were removed according to SectionII. Electron microscopy was tested using procedure of Section II. E.Extraction of analytes and analysis was performed according to SectionIII.

Extracts of the denuders were analyzed for PAH by adapting thedual-fluorescence technique developed by Mahanama et al. for analysis ofsemi-volatile PAH from naphthalene to chrysene Intern. J. Environ. Anal.Chem., 63: (1994). A high performance liquid chromatograph HewlettPackard Model 1090 M was used with a Vydac 201TP5215 column. Thegradient program increased the eluant strength from 38% acetonitrile, 2%THF in water, to 95% acetonitrile, 5% THF, over 24 min at 0.5 mL/min.From 25 to 33 minutes the flow increased linearly to 1 mL/min. After 4.5min the flow rate returned to 0.5 mL/min, and the mobile phasecomposition returned to the initial condition during the next twominutes. A 12-minute equilibration at 0.5 mL/min followed. The columnwas maintained at 30.8° C.

A. PAH Concentrations in Indoor Air and Simulated ETS

Table 8 summarizes the gas phase concentration data obtained with theIOVPS for indoor air with no combustion sources and simulated ETS. Theranges and average concentrations are listed. PAH concentrations weretypically at least three times higher in ETS than in the relativelyclean room air of the laboratory. The concentration ranges are similarto those reported by other workers for indoor air with ETS.

TABLE 8 Concentration Ranges for Gas Phase PAH in ng/m³ Indoor airEnviron. Tobacco Smoke PAH Min. Max. Avg. Min. Max. Avg. Naphthalene 162545 338 784 1690 1099 1-Methylnaphthalene 43 161 89 334 748 4852-Methylnaphthalene 67 220 142 526 931 719 Biphenyl 4.1 62 25 45 423 189Acenaphthene & 3.3 18 8.3 2.7 134 70 acenaphthylene Fluorene 4.1 17 8.257 267 129 Phenanthrene 18 38 23 43 151 99 Anthracene 0.1 0.6 0.4 3.9 2213 Fluoranthene 3.5 9.8 6.5 3.7 13 10 Pyrene 2.2 4.6 3.0 14 64 44 Benz(a) anthracene 0.1 0.1 0.4 0.2 1.1 0.4 Chrysene 0.8 2.0 1.4 0.9 10 5.8

B. Phase Distributions and “Blow-off” of PAH in Indoor Laboratory RoomAir

Table 9 below presents phase distribution data for phenanthrene, pyreneand chrysene in indoor laboratory room air samples collected at 20 L/minfor 3 hours (filter face velocity=33 cm/sec) during which the IOVPS anda filter-sorbent bed sampler operated for 3 hours.

TABLE 9 Phase Distributions of PAH in Indoor Laboratory Room Air PAHIOVPS Filt-Sorb Phenanthrene 0.097 0.033 Pyrene 0.157 0.053 Chrysene0.247 0.052 (a) Indoor laboratory room air sampled at 20 L/min for 3hours

The particulate fractions were much lower for this environment than forETS, but the sampling conditions, face velocities and sampling times, aswell as the chemical composition, were very different. The particulatefractions obtained with the filter-sorbent bed sampler were smaller forall three PAH than obtained using the IOVPS. The discrepancy decreasedas the PAH volatility decreased. Two other parallel sampling experimentsalso yielded pre-sorbent-bed filter samples that had lower PAHconcentrations than the filter samples obtained with the IOVPS. The dataare consistent with PAH volatilization from the particles (“blow-off”)during sampling with the filter-sorbent bed. Post-filter denuders werenot used with the IOVPS in these experiments, so blow-off from theIOVPS-collected particles could not be assessed. However, in a separateexperiment using the configuration shown in FIG. 2 at face velocity of17 cm/sec (10 L/min, 6 hours) detectable amounts of phenanthrene,pyrene, benz(a)anthracene and chrysene were found an a post-filterdenuder. Since these compounds were not detected on the second denuder,they must have desorbed from the particles during sampling.

C. Simulated Field Test for Phase Distributions for PAH in EnvironmentalTobacco Smoke

Simulated environmental tobacco smoke was sampled at 16 and 20° C. in asealed (0.03 air exchange per hour, measured by SF₆ injection) 36 m³environmental chamber. A smoking machine (Arthur D. Little, Inc.,) wasused in the center of the room, about 4 feet above the floor. Threereference cigarettes, Kentucky reference type 1R4F were machine-smokedsequentially at one 35 mL puff per minute. The mainstream smoke wasventilated outside the chamber, while the side stream smoke was emittedinto the chamber. Two IOVPSs were placed about 2 feet apart, with theirinlets about two feet above the floor. The samplers operated for onehour at 5 L/min starting about 20 minutes after the last cigarette wasextinguished. A filter-sorbent bed sampler was located about 2 metersfrom the IOVPS and operated at 5 L/min during the same period.

In a separate experiment in the 36 m³ chamber just one IOVPS operatedunder the same conditions. A different chamber (20m³) was also used tosample ETS with the IOVPS for method development. In that chamber fourcommercial filter cigarettes were machine-smoked using the same smokingcycle (one every 25 minutes) over a 2 hour period the IOVPS operated at5 L/min for one hour during that time.

Table 10 presents phase distribution data for simulated environmentaltobacco smoke sampled at 16° C.

TABLE 10 Phase Distributions of PAH in Environmental Tobacco Smoke gasparticles fraction in PAH ng/m³ ng/m³ particles Naphthalene 822 <17<0.02 1-Methylnaphthalene 334 <12 <0.04 2-Methylnaphthalene 526 <10<0.02 Acenaphthene & 72.2 <1.4 <0.02 acenaphthylene Fluorene 56.5 <1.7<0.02 Phenanthrene 43.1 <5.2 <0.11 Anthracene 3.85 <0.1 <0.03Fluoranthene 3.73 2.3 0.38 Pyrene 13.8 3 0.18 Benz (a) anthracene 0.1510.4 0.99 Chrysene 0.86 30.1 0.97 (a) Sampled at 5 L/min for 1 hour

Both gas and particle phase data are average values for the co-locatedsamplers when the IOVPS operated in the 36 m³ chamber for one hour at 5L/min with face velocity =8 cm/sec. None of the more volatile PAH fromnaphthalene to anthracene were detected on the ETS particles, butfluoranthene and pyrene were found in both phases. Very littlebenz(a)anthracene and chrysene were found in the gas phase for ETS.Generally, the particulate fraction increased as molecular weightincreased and vapor pressure decreased. No detectable amounts of PAHwere found on the second filters or the post-filter denuders. No“blow-off’ of particulate PAH onto the backup filter substrate ordownstream denuder was observed for this experiment. In a separateexperiment using the same IOVPS configuration but with the chamber at20° C., fluoranthene, pyrene and chrysene were detected on thepost-filter denuder, indicating that some blow-off occurred. The amountsfound on the post-filter denuder averaged 16% of the total particulatePAH concentrations.

F. Limits of Detection

Because of the development of a new cleanup technique and thesensitivity of a newly-developed dual fluorescence detector highperformance liquid chromatography method, good precision has beenobtained with the sampler, for determination of the phase distributionof PAH in indoor air and ETS, in as little as one hour of sampling.Detection limits for phenanthrene, anthracene, pyrene and chrysene were10, 0.1, 0.8 and 0.4 ng/m³ respectively, for gas phase concentrations.Particulate phase detection limits for the same compounds were 2.6, 0.5,0.7 and 0.5 ng/m³, respectively for single channel IOVPS at flow ratesof 10 L/min.

G. Reproducibility of PAH Concentration Measurements

Reproducibility of PAH concentration measurement was determined andresults are seen in Table 11.

Table 11 presents PAH concentrations obtained from two co-located IOVPSthat simultaneously sampled simulated environmental tobacco smoke. Fordenuder extracts of the upstream denuder the coefficient of variationranged from 5% for 1-methylnaphthalene to 31% for pyrene and averaged14%. The high value for pyrene could be due to its co-elution with oneof the methyl derivatives of phenanthrene. The fluorescence excitationand emission wavelengths for pyrene were chosen from the edges of itsresponse envelope so that the methylphenanthrene interference wasminimized. The poor quantum yield for pyrene under that conditionprobably contributed to its high variability. The higher-than-averagecoefficient of variation for biphenyl may be due to its co-elution with2-methylnaphthalene which was always found at higher concentrations thatbiphenyl. Most of the semi-volatile PAH were not detected in theparticle phase. However, the four that were detected had averagecoefficient of variation of 16%.

TABLE 11 Reproducibility of PAH Concentration Measurements in SimulatedEnvironmental Tobacco Smoke Gas phase Particle phase Std Std Avg. DevCoeff Avg. Dev Coeff PAH ng/m³ ng/m³ of Var. ng/m³ ng/m³ of Var.Naphthalene 822 82 9.9 bd — — 1-Methyl- 334 18 5.4 bd — — naphthalene2-Methyl- 526 40 7.6 bd — — naphthalene Biphenyl 45 10 21.6 bd — —Acenaphthene 72 12 16.5 bd — — and acenaphthylene Fluorene 56.5 3.6 6.4bd — — Phenanthrene 43.1 6.7 15.5 bd — — Anthracene 3.85 0.53 13.8 bd —— Fluoranthene 3.73 0.53 14.2 2.3 0.07 3.1 Pyrene 13.8 4.3 30.9 3.0 0.311.1 Benz (a) anth- 0.15 0.028 18.8 10.4 3.7 35.1 racene Chrysene 0.860.067 7.8 30.1 3.5 11.7 Average: 14.0 15.2 Std Dev: 7.4 13.8 bd = belowthe lower limit of detection

E. Comparison of the IOVPS to a Filter-Sorbent Bed Sampler

Comparison of the IOVPS to a filter-sorbent bed sampler for collectionof gas-phase PAH in indoor air at two flow rates is shown in Table 12.

TABLE 12 Comparison of the IOVPS to a Filter-Sorbent Bed Sampler^(a)Uncer- Denuder/Sorbent Denuder/Sorbent tainty ratio ratio PAH % 10 L/min20 L/min Naphthalene 11.0 0.83 ± 0.09 0.68 ± 0.07 1-Methylnaphthalene11.7 1.11 ± 0.13 0.80 ± 0.09 2-Methylnaphthalene 11.7 1.03 ± 0.12 0.70 ±0.08 Biphenyl 22.7 1.03 ± 0.23 0.60 ± 0.13 Acenaphthene and 14.0 0.87 ±0.12 0.72 ± 0.10 acenaphthylene Fluorene 30.4 0.95 ± 0.29 0.85 ± 0.26Phenanthrene 14.5 1.18 ± 0.17 0.94 ± 0.14 Anthracene 12.7 0.94 ± 0.120.95 ± 0.12 Fluoranthene 12.7 1.00 ± 0.13 0.84 ± 0.11 Pyrene 29.6 1.05 ±0.31 0.84 ± 0.25 Chrysene 20.4 bd^(b) 0.65 ± 0.13 Average (All PAH) 1.00 ± 0.10^(c)  0.78 ± 0.12^(c) ^(a)Three-hour sampling periods on twodifferent days ^(b)Below the detection limit ^(c)Standard deviationderived from the average of denuder/sorbent ratios

Comparison data from sampling indoor laboratory room air on twodifferent days are presented in Table 12 for two flow rates, 10 and 20L/min. Three-hour sampling periods were used for each experiment. Thedata indicate that the IOVPS traps and recovers semi-volatile PAHquantitatively when its capacity is not exceeded. At 10 L/min thedenuders and sorbent trapped the same amounts of semi-volatile PAE. Theratio of detectable PAH measured with the denuders to PAH collected bythe sorbent bed was 1.00±0.10. Therefore, the IOVPS-derived gas-phasePAH concentrations agreed with the conventional sampler results at thisflow rate and sampling time. The data show no apparent samplingartifacts.

Indoor air sampling with the IOVPS for three hours at 20 L/min yieldedgas-phase PAH concentrations (summed from three serial denuder sections)that averaged 78±13% of those derived from the sorbent bed. Thedenuder-derived PAH concentrations averaged 73±9% of the sorbent-derivedconcentrations for PAH more volatile than phenanthrene (thenaphthalenes, acenaphthene, acenaphthylene, biphenyl and fluorene). Thecapacity limits for these species had been exceeded under the conditionsof this experiment, as shown in FIG. 9. Denuder-derived concentrationsfor phenanthrene and the less volatile PAH from the IOVPS averaged84±13% of the sorbent-derived values for the same experiment. Thataverage is heavily dependent on the value for chrysene, but the gasphase concentrations of chrysene for the two sample types are well abovethe limits of quantitation and appear to be statistically different.Since the data of FIG. 9 indicate that phenanthrene was collected in thefirst two of three denuder sections with >90%-efficiency under thesampling conditions of this experiment, operation of the IOVPS withthree serially-connected sections is expected to lead to >99%efficiency. However, the apparent sorbent bed concentration may havebeen increased by “blow off’ artifacts from the filter-collectedparticulate phenanthrene and less volatile species fluoranthene throughchrysene.

EXAMPLE 1 Field Test for Nicotine in Environmental Tobacco Smoke

The IOVPS was used in the configuration shown in FIG. 2 to determinenicotine in simulated environmental tobacco smoke. This configurationwas intended to collect nicotine in the denuder sections and on thefilter. Any nicotine blown-off the filter was trapped by the downstreamdenuder section. The denuder sections had been coated with ground XAD-4resin as described above. Denuders were coated with XAD-4 as describedabove. Denuders were extracted by sonication with spectroscopic-gradeethyl acetate with 0.01% triethylamine. The triethylamine preventsadsorption of nicotine to glass surfaces. Quinoline was added at thetime of extraction as an internal standard to correct for any volatilitylosses during sample preparation. The extracts were filtered with aMillipore Teflon filter of pore size 0.5 micrometers, filter type FHUP,to separate the XAD-4 coating from the extracts. The extracts wereconcentrated to approximately 500 microliters.

Extracts of denuders were analyzed for nicotine using anitrogen-phosphorous detector mounted on a Shimadzu GC-9A gaschromatograph with a DB-Wax 30 in×0.32 mm fused silica capillary column.

The gas flow rates were: helium (primary carrier),1 mL/min; helium(make-up), 15 mL/min; hydrogen, 4 mL/min; and air, 75 mL/min. Thehydrogen and air flow rates were controlled through the Shimadzu GC-9A.The helium primary carrier and make-up gases were bypassed into aScientific Glass Engineering Unijector where their flow rates wereregulated. The injector was operated in splitless mode. Both theinjector port and the detector base were set to 250° C.

The column temperature program started at initial conditions of 175°C.After 5 minutes, the temperature was increased linearly at a rate of0.5° C./min for 10 minutes until the column temperature reached 180° C.

A Detector Engineering Technology (DET) nitrogen-phosphorous detectorwith a ceramic thermionic source was installed on the flame ionizationdetector base of the Shimadzu GC-9A. Prior to sample analysis, theheating current of the DET Detector Current Supply, Model 4000, wasslowly increased until ignition of hydrogen-air chemistry was achieved.Typical operating currents were approximately 3 amperes.

A Shimadzu Chromatopac C-R3A Data Processor was used to integrate peakareas during each sample run. Depending on the concentration of thesample, the sensitivity range and attenuation were manually adjusted onthe Chromatopac C-R3A to optimize chromatogram output. Under theseconditions, both nicotine and quinoline used as internal standard elutedbetween 5 and 6 minutes with excellent peak separation.

Two complete sampling trains were co-located and operatedsimultaneously. Three reference cigarettes were smoked sequentially in asealed environmental chamber (36 m³). About 45 minutes elapsed beforesampling began. Air was pulled through the IOVPS at 5 L/min for onehour. Nicotine was determined in denuder sections and filters using thedescribed method. The results are shown in Table 13, and they indicatethat the IOVPS can be used to trap nicotine from both the gas andparticle phases. Parallel sampling was conducted using Hammond et al.,method (Atmospheric Env., 21: 457-462, (1987).

TABLE 13 Nicotine in Environmental Tobacco Smoke IOVPS microgram m⁻³Hammond microgram m⁻³ Denuder d1 (gas) 15.7 gas 23.6 Denuder d2 <0.24Filter (particles) 0.64 particles 0.89 Denuder d3 <0.24

The data can be used to calculate the phase distribution of nicotine inETS. Both gas and particulate nicotine levels measured during the sameexperiment with a single Hammond sampler were somewhat higher thanobtained with the IOVPS.

EXAMPLE 2 Nicotine: Phase Distribution in ETS

This study was conducted in a 20 m³ stainless steel environmentalchamber with a surface area of 45.2 m². Six mixing fans (three inchestall) were staggered at ⅓ and ⅔ of the wall height with the axis of eachfan positioned at a 45° angle from the wall surface. All fans blew airin the same circular direction around the chamber. The mixing fans wereconnected in series to a variable voltage controller at a setting of 50volts and operated during, both the smoking and sampling periods. Thecirculation vents and chamber door were sealed with duct tape during theexperiment to minimize the air exchange rate. The chamber temperatureaveraged 24° C., and the relative humidity was approximately 22%. Afully automated smoking machine (Lawrence Berkeley Laboratory, Berkeley,Calif.) was connected to a puffer (Model ADL/II, Arthur D. Little,Cambridge, Mass.) and positioned on the floor in the center of the room.A brand of popular filtered commercial cigarettes were conditioned at60% relative humidity for more than 72 hours over an aqueous saturatedNaBr solution. The ignition of the first cigarette was designated aszero minutes. The cigarettes were sequentially burned for approximately11 minutes each starting at zero, 12, and 22 minutes. The cigarettessmoldered from an average length of 7.9 cm until they were extinguishedat an average butt length of 3.1 cm.

Five integrated organic vapor-particle samplers inserted and removed insequence collected nicotine for the first 189 minutes. The ventilationduct and chamber door was sealed shut with duct tape during theexperiment to minimize the air exchange rate. At 189 minutes, thechamber door was opened.

Gas and particulate phase nicotine concentrations were measured as afunction of time using the IOVPS which consisted of two denudersfollowed by two 47 mm Teflon-coated glass fiber filters. The IOVPS wasinserted into the chamber through a port on the wall, and the samplerinlet extended approximately 60 cm into the room from the wall. Thedenuders were coated with ground XAD-4 (Alltech Associates, Inc.,Deerfield, Ill.) for the collection of gas phase nicotine, with thesecond denuder serving, as a backup. The first glass fiber filtercollected particulate nicotine, and the second glass fiber filter wascleaned and coated with an aqueous 4% NaHSO₄ solution (with 5% ETOH towet the filter) for collection of gas phase nicotine blown off (or“volatilized” or “evaporated”) from the particles on the upstreamfilter. Sampling at 5 L/min via the house vacuum regulated through amass flow controller occurred over five periods: 9-19 min, 20-30 min,31-41 min, 89-109 min, and 169-189 min. Newly coated denuders and cleanfilters were used for each sampling period. Unexposed XAD-4-coateddenuders, Teflon-coated class fiber filters, and NaHSO₄-treatedTeflon-coated glass fiber filters were set aside for blank measurements.

The denuders were extracted by filling them with ethyl acetate(approximately 20 ml) containing 0.01% v/v TEA, adding 27 μg ofquinoline, and capping the ends. The denuders were then sonicated in awarm water bath (40° C.) for 15 minutes. The extracts were filteredthrough 47 mm Teflon filters (Type FHUP, Pore Size 0.5 μm, MilliporeCorporation, Bedford, Mass.) to remove any particles of the XAD-4denuder coating, then a second extraction and filtration was performed.The filtrates were concentrated using a rotary evaporator (BrinkmannRotavapor -R) with a water bath set to 42° C. Final volumes ranged from183 to 428 μl. Extracts were transferred to vials for storage andanalysis.

The 47 mm Teflon-coated glass fiber filters were extracted by cuttingthem into 0.5 cm² pieces and placing them into a 9 ml conical vial,adding 3 ml of ethyl acetate with 0.01% v/v TEA, and spiking them with27 μg of quinoline. The glass fiber filters were sonicated for 15minutes and filtered using a Teflon filter. After a second extractionand filtration, the extracts were evaporated to final volumes rangingfrom 244 to 427 μl and transferred to vials for storage and analysis.

The 47 mm NaHSO₄-treated Teflon-coated class fiber filters wereextracted using the method outlined by Hammond et al in AtmosphericEnv., 21: 457-462. (1987). Filters were spiked with 27 μg of quinolinein ethyl acetate, and approximately one minute was allowed for the ethylacetate to evaporate at room temperature. The intact 47 mmNaHSO₄-treated glass fiber filters were inserted into test tubes. Toremove nicotine from the acid-coated filter, 100 μl ETOH was added towet the filter, followed by 2 ml water. After one minute of vortexing, 2ml of 10N NAOH was added to deprotonate nicotine in aqueous solution.The mixture was vortexed for one minute, then 500 ml ammoniated hexanewas added. In a fashion similar to TEA, ammonia suppresses adsorption ofnicotine onto glass. Another minute of vortexing is performed, therebytransferred nicotine to the organic hexane layer. The hexane wastransferred to a vial for storage and analysis. Final volumes of hexaneranged from 190 to 310 μl.

All samples were analyzed on the day of extraction using a Shimadzu gaschromatograph obtained from Shimadzu Corporation, Kyoto, Japan. Thehelium primary carrier gas flow rate was set to 1 ml/min through aScientific Glass Engineering, Unijector Control Module (SGE Inc.,Austin, Tex.). Samples were injected with a 5 μl SGE syringe into theShimadzu injector under splitless injection mode with septum purge.Injection volumes were 1.0±0.1 μl. The injector temperature was set to250° C. Compounds were separated on a DB-WAX fused silica capillarycolumn (30 m×0.32 mm, 0.25 μm film thickness, J&W, Folsom, Calif.). Theoven temperature was pro-rammed at 165° C. for 7 minutes and thenincreased at 17.5° C./min to a final temperature of 200° C. for 3minutes.

A DETector Engineering Technology (DET, Walnut Creek, Calif.) thermionicnitrogen-phosphorous detector (NPD) was mounted on top of the Shimadzuflame ionization detector base. The additional gas flow rates suppliedto the detector were: helium make-up gas, 15 ml/min; hydrogen, 4 ml/min;air, 75 ml/min. The detector heating block was set to 250° C. The NPDwas powered by a DET current supply (Model 4000). Operating currentsused in these analyses ranged from 3.02 to 3.04 amperes. Signals wereinterpreted by the Shimadzu electrometer on the highest sensitivityrange and plotted by the Shimadzu Chromatopac C-R3A data processor. TheC-R3A processor was programmed to integrate by peak area. Nicotine andquinoline eluted at approximately 5.4 min and 6.1 min respectively, withexcellent peak separation. New nicotine and quinoline standards in ethylacetate with 0.01% v/v TEA were prepared for the analyses, and the samestandards were used for the different extractions for consistency. Allextractions and analyses were completed in nine days. Nicotine andquinoline external standards were injected periodically between samplesto obtain a drift correction for nicotine and quinoline responsefactors. Response factors decreased very slowly with time due to thedecrease in sensitivity of the NPD bead with time. A linear regressionanalysis of the response factors was performed for each day of analysisand factored into nicotine and quinoline mass calculations for allinjected samples.

All data were corrected for the percentage recovery of quinolineinternal standard. Quinoline is a convenient internal standard becauseit is chemically similar to nicotine, but it has been reported thatquinoline is present at about 1% of the nicotine concentration in ETS(Caka et al., Environ. Sci. Technol., 24:1196-1206. Since quinoline wasadded at levels similar to the amount of nicotine found in each sampler,errors due to quinoline in ETS were negligible in most cases. However,corrections for quinoline were applied when nicotine was underestimatedby more than 1%. Except where indicated, blank values were subtractedfrom the nicotine masses. Percent recoveries, blank masses for nicotine,limits of detection, and limits of quantitation are listed in Table 14.

TABLE 14 Results of Quinoline Phase Distribution Study Sampler Recovery(%) Blank (μg) LOD (μg) LOD (μg) Sorbent Tubes 65-85 0.12 4 × 10⁻⁴ 1.3 ×10⁻³ Denuders  68-107 0.32 7 × 10⁻² 2.5 × 10⁻¹ 47 mm Uncoated 76-95b.d.* 4 × 10⁻⁴ 1.5 × 10⁻³ Filters 47 mm Bisulfate 44-71 0.08 5 × 10⁻⁴1.6 × 10⁻³ Filters High Vol. Filter 52-88 b.d.* 4 × 10⁻⁴ 1.3 × 10⁻³Sheets Stainless Steel 74-89 0.90 5 × 10⁻⁴ 1.6 × 10⁻³ Sheets *below thelimit of detection.

The gas-particle phase distribution was measured by the IOVPS system.The two denuders collected gas phase nicotine with the second denuderserving as a backup for breakthrough. The first glass fiber filtercollected particle phase nicotine, and blank values were below detectionso no correction was made. The second glass fiber filter was coated with4% NaHSO₄ to collect volatilized nicotine from the particles on thefirst filter. Results are shown in Table 15.

TABLE 15 Gas Phase Distribution Time 1st 2nd 1st 2nd Period IntervalDenuder Denuder Filter Filter 1  9-19 min 263 0 2.7 0 2 20-30 min 406  0.5 4.9 0 3 31-41 min 449   6.3 5.0 0 4 89-109 min  131 0 1.6   0.2 5169-189 min   74 0 4.0 0 Denuder and filter concentrations are in μg/m³

Nicotine concentrations were taken from IOVPS gas phase measurements.Nicotine was collected in a glass sidestream smoke apparatus (225 cm³volume), and an emission factor for the same cigarette brand wasconverted into an emission rate of 27.4 mg/h. The ventilation rate dueto chamber leakage was determined before the experiment by monitoringSF₆ tracer gas decay over 13 hours. The leakage rate was 0.152 m³/h.Ventilation due to sampling was 0.232 m³/h, and the loss rate due todeposition (v_(t)×surface area), which is analogous to ventilation, was0.576 m³/h. This yielded a total ventilation rate, Q_(T), of 0.96 m³/h.

What is claimed is:
 1. A method for preparation of a sorbent forsampling of semi-volatile organic gases and particulate components, saidsorbent comprising macroreticular resin agglomerates of randomly packedmicrospheres with a continuous porous structure of particles ranging insize from 0.5 to 10 microns, said method comprising steps: a) preparingparticles of a macroreticular resin or a combination of themacroreticular resin with an activated carbon, said particles ranging insize between 0.5 and 10 microns, by: i. grinding the macroreticularresin or a combination thereof with the activated carbon to theparticles having a size of 10 microns or lower; ii. suspending saidground macroreticular polymeric resin or the combination thereof in anorganic solvent, wherein said resin is selected from the groupconsisting of a styrene divinylbenzene polymer or copolymer, apolyaromatic polymer or copolymer, polystyrene polymer or copolymer,ethyl vinylbenzene, ethyl vinylbenzene-divinyl benzene,methylmethacrylate, methacrylate-divinylbenzene, methacrylate-styrene,2,6-diphenyl-p-phenylene oxide, bonded or non-bonded silica, alumina andfluoracil, said resin having a pore size between 45 to 2000 Å and asurface area between 35 and 2000 m²/g; iii. purifying said suspension ofstep (ii) by a solvent extraction or sonication; iv. filtering thesuspension through a 0.5 micron filter to remove all particles of sizesbelow 0.5 micron; and v. recovering a fraction remaining on the filter;b) vacuum or air drying the fraction remaining on the filter; and c)recovering the dry fraction as the sorbent for sampling of thesemi-volatile organic gases and particulate components.
 2. The method ofclaim 1, wherein the resin is 2,6-diphenyl-p-phenylene oxide having apore size 2000 Å and a surface area 35 m²/g.
 3. The method of claim 1,wherein the resin is the styrene divinylbenzene copolymer having thepore size 50 Å and the surface area 780 m²/g, or 85 Å and 350 m²/g, or90 Å and 350 m²/g, or 200 Å and 100 m²/g.
 4. The method of claim 1wherein the resin is the polyaromatic or polystyrene polymer orcopolymer.
 5. The method of claim 4, wherein the resin is thepolyaromatic copolymer having a pore size 500 Å and a surface area 650m²/g or the polystyrene polymer having a surface area 750 m²/g.
 6. Themethod of claim 1, wherein the resin is ethyl vinylbenzene or ethylvinylbenzene-divinyl benzene.
 7. The method of claim 6, wherein theresin is ethyl vinylbenzene-divinylbenzene having a pore size 45 Å and asurface area 570 m²/g or ethyl vinylbenzene-divinylbenzene having asurface area 735 m²/g.
 8. The method of claim 1 wherein the resin ismethylmethacrylate, methacrylate-divinylbenzene, ormethacrylate-styrene.
 9. The method of claim 8, wherein the resin is themethylmethacrylate having a pore size 80 Å and a surface area 450 m²/gor the pore size 250 Å and the surface area 140 m²/g,methacrylate-divinylbenzene having a surface area 320 m²/g ormethacrylate-styrene having a surface area 70 m²/g.
 10. The method ofclaim 1, wherein the particles range in size from between 1 and 7microns.
 11. The method of claim 10, wherein a surface to volume ratioof the particles is 200,000 to 4,000 cm⁻¹.
 12. The method of claim 10,wherein the sorbent is the combination of the activated carbon and themacroreticular polymeric resin.
 13. The method of claim 12, wherein theactivated carbon is graphite or black carbon.
 14. The method of claim 3wherein the styrene divinylbenzene copolymer has the pore size 50 Å andthe surface area 780 m²/g.